Categories:: String & Binary Functions (General)

TRIM¶

Removes leading and trailing characters from a string.

Note

To remove characters in a string, you can use the REPLACE function.

See also:: LTRIM , RTRIM

Syntax¶

TRIM( <expr> [, <characters> ] )

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Arguments¶

expr

A string expression to be trimmed.

characters

One or more characters to remove from the left and right side of expr.

The default value is ' ' (a single blank space character). If no characters are specified, only blank spaces are removed.

Returns¶

This function returns a value of VARCHAR data type or NULL. If either argument is NULL, returns NULL.

Usage notes¶

You can specify the characters in characters in any order.
A specification of ' ' in characters does not remove other whitespace characters (such as tabulation characters, end-of-line characters, and so on). Explicitly specify these characters to remove them.

To remove whitespace, the characters must be explicitly included in the argument. For example, ' $.' removes all leading and trailing blank spaces, dollar signs, and periods from the input string.

Collation details¶

Collation is supported when the optional second argument is omitted, or when it contains only constant whitespace.

The collation specification of the returned value is the same as the collation specification of the first argument.

Examples¶

Remove leading and trailing * and - characters from a string:

SELECT TRIM('*-*ABC-*-', '*-');

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+-------------------------+
| TRIM('*-*ABC-*-', '*-') |
|-------------------------|
| ABC                     |
+-------------------------+

Remove leading and trailing whitespace from a string. This example encloses the strings in > and < characters to help you visualize the whitespace. It also shows that the function returns NULL for NULL input.

CREATE OR REPLACE TABLE test_trim_function(column1 VARCHAR);

INSERT INTO test_trim_function VALUES ('  Leading Spaces'), ('Trailing Spaces  '), (NULL);

SELECT CONCAT('>', CONCAT(column1, '<')) AS original_values,
       CONCAT('>', CONCAT(TRIM(column1), '<')) AS trimmed_values
  FROM test_trim_function;

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+---------------------+-------------------+
| ORIGINAL_VALUES     | TRIMMED_VALUES    |
|---------------------+-------------------|
| >  Leading Spaces<  | >Leading Spaces<  |
| >Trailing Spaces  < | >Trailing Spaces< |
| NULL                | NULL              |
+---------------------+-------------------+